Target Details CD80

The vertebrate immune system has an important self check mechanism that prevents it from destroying the host own immune system and regulatory T cells are part of this regulatory suppressive control by interacting with CD80 and CD86 (1). The cytotoxic T lymphocyte antigen 4 (CTLA4) is a protein that is expressed on regulatory T lymphocytes and is involved in restraining the immune response when needed and in tachyphylaxis and tolerance. The Fox3p-CD4+ (CD25+CD4+) regulatory T cells (Tregs) express transcription factor Foxp3 suppress aberrant immune responses as seen in autoimmune diseases and allergy (2). CD80 is a co-stimulatory ligand that interacts with CD28 and cytotoxic lymphocyte antigen 4 (CTLA4) in the regulation of T cell response. CD80 along with CD86 expression on antigen presenting cells (APCs) have the ability to augment T cell responses through interactions with CD28 (3) or inhibit T cell responses through interaction with CTLA-4 (4). The CD80/CD86 interaction with CD28/CTLA-4 occurs in the contact area between T cells and APC in parallel with T cell antigen receptor interaction with MHC-peptide complexes and LFA-1 interaction with ICAM-1 (4). The CTLA4 expressed in Fox3p positive tregs is critically required for their in vivo and in vitro suppression which is mediated at least in part by CTLA4 dependent down regulation of CD80 and CD86 in antigen presenting cells. CD80 and CD86 are cell surface markers expressed on human dendritic cells and mature B-lymphocytes and they play a critical role in stimulating T lymphocyte response by their interaction with the ligand CTLA4 and CD28. CD80 and CD86 are up-regulated during the process of dendritic cell maturation and are over expressed in variety of lymphocytic neoplasm (6). CD80 expression is selectively increases in freshly prepared spleen B cells treated with LPS for 9-12 hours and when they are exposed to X-radiation, whereas CD86 is not affected and only slight increase in CD54, major histocompatibility complex class II, CD11a or surface immunoglobulin M was observed (5). CD80/CD86 co-stimulation is important for the immune response to vesicular stomatitis virus, herpes simplex virus and influenza virus. CD80/CD86 serve a a means of adenovirus entry on human dendritic cells and the interaction of CD80/CD86 with CTLA4 is also important in long-term control of murine gammaherpesvirus-68 virus. CD80 provides a regulatory signals for T lymphocytes as a consequence of binding to the CD28 and CTLA4 ligands of T cells. CD80 is a 321 amino acid (39 kDa) protein expressed on Treg.Synonyms: Activation B7-1 antigen, B7-1, B7.1, BB1, CD28LG, CD28LG1, CTLA-4 counter-receptor B7.1, LAB7, T-lymphocyte activation antigen CD80